1) Field of the invention
The present invention relates to a method of recovering rare earth elements from oxidized scrap of a permanent magnet.
2) Background of Related Art
Rare earth magnets have been extensively used in various fields from typical home appliances to peripheral terminals of large-sized computers or medical instruments. The rare earth magnet is one of significant important electronic materials to realize advanced technologies. Recently, as computers or telecommunication appliances are realized in small size and light weight, the rare earth magnet has been realized with high precision in small size. In addition, as the use of the rare earth magnet is enlarged, the demand for the rare earth magnet is rapidly increased.
In general, after the rare earth magnet is molded and sintered in predetermined size, the rare earth magnet is formed in predetermined size and shape through a mechanical machining process or a grinding process and the surface treatment process such as a plating process or a painting process is performed with respect to the rare earth magnet, so that the rare earth magnet is realized as a product. The weights of scraps, such as molding exposure powders, a sintering characteristic defective product, a machining defective product, or a plating defective product, made during the above processes occupy several tens of percentages of the weight of an original source material, and sludge (machining or grinding fragments) generated during the mechanical process or the grinding process approximates several tens of percentages of a product source material. Therefore, the recovering or recycling process of rare earth elements from the rare earth scraps and sludge is extremely important to save resources, reduce industrial waste, and lower the price of the rare earth magnet.
According to the related art, in order to extract neodymium (Nd) from the rare earth magnet, various schemes such as an elution scheme, a chromatography scheme, a precipitation scheme, and a solvent extraction scheme have been attempted. However, only the minimum of Nd is extracted or Nd is extracted at a low rate, so that Nd may not be used in recycling industries.
As the related art, there is provided Korea Patent Registration No. 10-1183579 (issued on Sep. 17, 2012) titled “High Efficient Nd Leaching Method using Ultrasonic Wave”.